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decoder_simple_MAP.m
资源名称：Turbomatlab.rar　[点击查看]
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上传日期：2013-06-30
资源大小：2149k
文件大小：5k
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传真(Fax)编程

开发平台：

Matlab

decoder_simple_MAP.m：源码内容
  1. %****************************************************************
  2. % 内容概述：利用硬件化的方式实现TURBO码的MAP译码
  3. %          未使用另外一个译码器反馈的外部信息 
  4. % 创 建 人：朱殿荣/QQ:235347/MSN:njzdr@msn.com
  5. % 单    位：南京邮电大学，通信工程系
  6. % 创建时间：2005年7月6日
  7. % 修改时间：
  8. % 参考文献：《数字通信－－基础与应用》
  9. % 版权声明：任何人均可复制、传播、修改此文件，同时需保留原始版权信息。
  10. %****************************************************************
  12. clear;
  13. x=[1.5 0.5 -0.6];
  14. y=[0.8 0.2 1.2];
  15. alpha=zeros(4,4);   %前向状态量度，4种可能状态，约束长度为3.zeros(S,k)
  16. alpha(1,1)=1;       %前向状态量度初始值为1，其他为0
  17. belta=zeros(4,4);   %后向状态量度，4种可能状态，约束长度为3.zeros(S,k)
  18. belta(1,4)=1;       %后向状态量度末尾值为1，其他为0
  19. gamma0=zeros(4,4); %后向状态量度，4种可能状态，约束长度为3,输入0.zeros(S,k)
  20. gamma1=zeros(4,4); %后向状态量度，4种可能状态，约束长度为3,输入1.zeros(S,k)
  21. pi=0.5;           %先验概率
  23. %k=1---------------------------------------------
  24. k=1;
  25. gamma0(1,k)=pi*exp(x(k)*(-1)+y(k)*(trellis_simple(-1,1)));
  26. gamma1(1,k)=pi*exp(x(k)*(1)+y(k)*(trellis_simple(1,1)));
  27. gamma0(2,k)=pi*exp(x(k)*(-1)+y(k)*(trellis_simple(-1,2)));
  28. gamma1(2,k)=pi*exp(x(k)*(1)+y(k)*(trellis_simple(1,2)));
  29. gamma0(3,k)=pi*exp(x(k)*(-1)+y(k)*(trellis_simple(-1,3)));
  30. gamma1(3,k)=pi*exp(x(k)*(1)+y(k)*(trellis_simple(1,3)));
  31. gamma0(4,k)=pi*exp(x(k)*(-1)+y(k)*(trellis_simple(-1,4)));
  32. gamma1(4,k)=pi*exp(x(k)*(1)+y(k)*(trellis_simple(1,4)));
  33. %for s=1:4
  34. %    gamma0(s,k)=pi*exp(x(k)*(-1)+y(k)*(trellis_simple(-1,s)));
  35. %    gamma1(s,k)=pi*exp(x(k)*(1)+y(k)*(trellis_simple(1,s)));
  36. %end
  37. %k=2---------------------------------------------
  38. k=2;
  39. gamma0(1,k)=pi*exp(x(k)*(-1)+y(k)*(trellis_simple(-1,1)));
  40. gamma1(1,k)=pi*exp(x(k)*(1)+y(k)*(trellis_simple(1,1)));
  41. gamma0(2,k)=pi*exp(x(k)*(-1)+y(k)*(trellis_simple(-1,2)));
  42. gamma1(2,k)=pi*exp(x(k)*(1)+y(k)*(trellis_simple(1,2)));
  43. gamma0(3,k)=pi*exp(x(k)*(-1)+y(k)*(trellis_simple(-1,3)));
  44. gamma1(3,k)=pi*exp(x(k)*(1)+y(k)*(trellis_simple(1,3)));
  45. gamma0(4,k)=pi*exp(x(k)*(-1)+y(k)*(trellis_simple(-1,4)));
  46. gamma1(4,k)=pi*exp(x(k)*(1)+y(k)*(trellis_simple(1,4)));
  47. alpha(1,k)=gamma0(1,k-1)*alpha(1,k-1)+gamma0(3,k-1)*alpha(3,k-1);%后一项为0
  48. alpha(2,k)=gamma1(1,k-1)*alpha(1,k-1)+gamma1(3,k-1)*alpha(3,k-1);%后一项为0
  49. %k=3---------------------------------------------
  50. k=3;
  51. gamma0(1,k)=pi*exp(x(k)*(-1)+y(k)*(trellis_simple(-1,1)));
  52. gamma1(1,k)=pi*exp(x(k)*(1)+y(k)*(trellis_simple(1,1)));
  53. gamma0(2,k)=pi*exp(x(k)*(-1)+y(k)*(trellis_simple(-1,2)));
  54. gamma1(2,k)=pi*exp(x(k)*(1)+y(k)*(trellis_simple(1,2)));
  55. gamma0(3,k)=pi*exp(x(k)*(-1)+y(k)*(trellis_simple(-1,3)));
  56. gamma1(3,k)=pi*exp(x(k)*(1)+y(k)*(trellis_simple(1,3)));
  57. gamma0(4,k)=pi*exp(x(k)*(-1)+y(k)*(trellis_simple(-1,4)));
  58. gamma1(4,k)=pi*exp(x(k)*(1)+y(k)*(trellis_simple(1,4)));
  59. alpha(1,k)=gamma0(1,k-1)*alpha(1,k-1)+gamma0(3,k-1)*alpha(3,k-1);%后一项为0
  60. alpha(2,k)=gamma1(1,k-1)*alpha(1,k-1)+gamma1(3,k-1)*alpha(3,k-1);%后一项为0
  61. alpha(3,k)=gamma0(2,k-1)*alpha(2,k-1)+gamma0(4,k-1)*alpha(4,k-1);%后一项为0
  62. alpha(4,k)=gamma1(2,k-1)*alpha(2,k-1)+gamma1(4,k-1)*alpha(4,k-1);%后一项为0
  63. %k=4---------------------------------------------
  64. k=4;
  65. alpha(1,k)=gamma0(1,k-1)*alpha(1,k-1)+gamma0(3,k-1)*alpha(3,k-1);
  66. alpha(2,k)=gamma1(1,k-1)*alpha(1,k-1)+gamma1(3,k-1)*alpha(3,k-1);
  67. alpha(3,k)=gamma0(2,k-1)*alpha(2,k-1)+gamma0(4,k-1)*alpha(4,k-1);
  68. alpha(4,k)=gamma1(2,k-1)*alpha(2,k-1)+gamma1(4,k-1)*alpha(4,k-1);
  69. % for belta,from k=3------------------------
  70. k=3;
  71. belta(1,k)=gamma0(1,k)*belta(1,k+1)+gamma1(2,k)*belta(2,k+1);%后一项为0
  72. belta(3,k)=gamma0(3,k)*belta(1,k+1)+gamma1(2,k)*belta(2,k+1);%后一项为0
  73. % for belta,from k=2------------------------
  74. k=2;
  75. belta(1,k)=gamma0(1,k)*belta(1,k+1)+gamma1(1,k)*belta(2,k+1);%后一项为0
  76. belta(3,k)=gamma0(3,k)*belta(1,k+1)+gamma1(3,k)*belta(2,k+1);%后一项为0
  77. belta(2,k)=gamma0(2,k)*belta(3,k+1)+gamma1(2,k)*belta(4,k+1);%后一项为0
  78. belta(4,k)=gamma0(4,k)*belta(3,k+1)+gamma1(4,k)*belta(4,k+1);%后一项为0
  79. % for belta,from k=1------------------------
  80. k=1;
  81. belta(1,k)=gamma0(1,k)*belta(1,k+1)+gamma1(1,k)*belta(2,k+1);
  82. belta(3,k)=gamma0(3,k)*belta(1,k+1)+gamma1(3,k)*belta(2,k+1);
  83. belta(2,k)=gamma0(2,k)*belta(3,k+1)+gamma1(2,k)*belta(4,k+1);
  84. belta(4,k)=gamma0(4,k)*belta(3,k+1)+gamma1(4,k)*belta(4,k+1);
  86. %calculate LLR-----------------------------------
  87. k=1;
  88. numerator=0;
  89. denominator=0;
  90. numerator=numerator+alpha(1,k)*gamma1(1,k)*belta(2,k+1);
  91. denominator=denominator+alpha(1,k)*gamma0(1,k)*belta(1,k+1);
  92. llr(k)=log10(numerator/denominator);
  94. %calculate LLR-----------------------------------
  95. k=2;
  96. numerator=0;
  97. denominator=0;
  98. numerator=numerator+alpha(1,k)*gamma1(1,k)*belta(2,k+1);
  99. numerator=numerator+alpha(2,k)*gamma1(2,k)*belta(4,k+1);
  100. denominator=denominator+alpha(1,k)*gamma0(1,k)*belta(1,k+1);
  101. denominator=denominator+alpha(2,k)*gamma0(2,k)*belta(3,k+1);
  102. llr(k)=log10(numerator/denominator);
  104. %calculate LLR-----------------------------------
  105. k=3;
  106. numerator=0;
  107. denominator=0;
  108. numerator=numerator+alpha(1,k)*gamma1(1,k)*belta(2,k+1);
  109. numerator=numerator+alpha(2,k)*gamma1(2,k)*belta(4,k+1);
  110. numerator=numerator+alpha(3,k)*gamma1(3,k)*belta(2,k+1);
  111. numerator=numerator+alpha(4,k)*gamma1(4,k)*belta(4,k+1);
  112. denominator=denominator+alpha(1,k)*gamma0(1,k)*belta(1,k+1);
  113. denominator=denominator+alpha(2,k)*gamma0(2,k)*belta(3,k+1);
  114. denominator=denominator+alpha(3,k)*gamma0(3,k)*belta(1,k+1);
  115. denominator=denominator+alpha(4,k)*gamma0(4,k)*belta(3,k+1);
  116. llr(k)=log10(numerator/denominator);
  117. llr